/* aes_encrypt.c - TinyCrypt implementation of AES encryption procedure */

/*
 *  Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *    - Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *
 *    - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 *    - Neither the name of Intel Corporation nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 */

#include "aes.h"
#include "constants.h"
#include "utils.h"

static const uint8_t sbox[256] = {
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16};

static inline unsigned int rotword(unsigned int a) { return (((a) >> 24) | ((a) << 8)); }

#define subbyte(a, o) (sbox[((a) >> (o)) & 0xff] << (o))
#define subword(a)    (subbyte(a, 24) | subbyte(a, 16) | subbyte(a, 8) | subbyte(a, 0))

int tc_aes128_set_encrypt_key(TCAesKeySched_t s, const uint8_t *k) {
  const unsigned int rconst[11] = {0x00000000, 0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000, 0x20000000, 0x40000000, 0x80000000, 0x1b000000, 0x36000000};
  unsigned int       i;
  unsigned int       t;

  if (s == (TCAesKeySched_t)0) {
    return TC_CRYPTO_FAIL;
  } else if (k == (const uint8_t *)0) {
    return TC_CRYPTO_FAIL;
  }

  for (i = 0; i < Nk; ++i) {
    s->words[i] = (k[Nb * i] << 24) | (k[Nb * i + 1] << 16) | (k[Nb * i + 2] << 8) | (k[Nb * i + 3]);
  }

  for (; i < (Nb * (Nr + 1)); ++i) {
    t = s->words[i - 1];
    if ((i % Nk) == 0) {
      t = subword(rotword(t)) ^ rconst[i / Nk];
    }
    s->words[i] = s->words[i - Nk] ^ t;
  }

  return TC_CRYPTO_SUCCESS;
}

static inline void add_round_key(uint8_t *s, const unsigned int *k) {
  s[0] ^= (uint8_t)(k[0] >> 24);
  s[1] ^= (uint8_t)(k[0] >> 16);
  s[2] ^= (uint8_t)(k[0] >> 8);
  s[3] ^= (uint8_t)(k[0]);
  s[4] ^= (uint8_t)(k[1] >> 24);
  s[5] ^= (uint8_t)(k[1] >> 16);
  s[6] ^= (uint8_t)(k[1] >> 8);
  s[7] ^= (uint8_t)(k[1]);
  s[8] ^= (uint8_t)(k[2] >> 24);
  s[9] ^= (uint8_t)(k[2] >> 16);
  s[10] ^= (uint8_t)(k[2] >> 8);
  s[11] ^= (uint8_t)(k[2]);
  s[12] ^= (uint8_t)(k[3] >> 24);
  s[13] ^= (uint8_t)(k[3] >> 16);
  s[14] ^= (uint8_t)(k[3] >> 8);
  s[15] ^= (uint8_t)(k[3]);
}

static inline void sub_bytes(uint8_t *s) {
  unsigned int i;

  for (i = 0; i < (Nb * Nk); ++i) {
    s[i] = sbox[s[i]];
  }
}

#define triple(a) (_double_byte(a) ^ (a))

static inline void mult_row_column(uint8_t *out, const uint8_t *in) {
  out[0] = _double_byte(in[0]) ^ triple(in[1]) ^ in[2] ^ in[3];
  out[1] = in[0] ^ _double_byte(in[1]) ^ triple(in[2]) ^ in[3];
  out[2] = in[0] ^ in[1] ^ _double_byte(in[2]) ^ triple(in[3]);
  out[3] = triple(in[0]) ^ in[1] ^ in[2] ^ _double_byte(in[3]);
}

static inline void mix_columns(uint8_t *s) {
  uint8_t t[Nb * Nk];

  mult_row_column(t, s);
  mult_row_column(&t[Nb], s + Nb);
  mult_row_column(&t[2 * Nb], s + (2 * Nb));
  mult_row_column(&t[3 * Nb], s + (3 * Nb));
  (void)_copy(s, sizeof(t), t, sizeof(t));
}

/*
 * This shift_rows also implements the matrix flip required for mix_columns, but
 * performs it here to reduce the number of memory operations.
 */
static inline void shift_rows(uint8_t *s) {
  uint8_t t[Nb * Nk];

  t[0]  = s[0];
  t[1]  = s[5];
  t[2]  = s[10];
  t[3]  = s[15];
  t[4]  = s[4];
  t[5]  = s[9];
  t[6]  = s[14];
  t[7]  = s[3];
  t[8]  = s[8];
  t[9]  = s[13];
  t[10] = s[2];
  t[11] = s[7];
  t[12] = s[12];
  t[13] = s[1];
  t[14] = s[6];
  t[15] = s[11];
  (void)_copy(s, sizeof(t), t, sizeof(t));
}

int tc_aes_encrypt(uint8_t *out, const uint8_t *in, const TCAesKeySched_t s) {
  uint8_t      state[Nk * Nb];
  unsigned int i;

  if (out == (uint8_t *)0) {
    return TC_CRYPTO_FAIL;
  } else if (in == (const uint8_t *)0) {
    return TC_CRYPTO_FAIL;
  } else if (s == (TCAesKeySched_t)0) {
    return TC_CRYPTO_FAIL;
  }

  (void)_copy(state, sizeof(state), in, sizeof(state));
  add_round_key(state, s->words);

  for (i = 0; i < (Nr - 1); ++i) {
    sub_bytes(state);
    shift_rows(state);
    mix_columns(state);
    add_round_key(state, s->words + Nb * (i + 1));
  }

  sub_bytes(state);
  shift_rows(state);
  add_round_key(state, s->words + Nb * (i + 1));

  (void)_copy(out, sizeof(state), state, sizeof(state));

  /* zeroing out the state buffer */
  _set(state, TC_ZERO_BYTE, sizeof(state));

  return TC_CRYPTO_SUCCESS;
}
